Bench grinder apparatus

ABSTRACT

A tool assembly includes a bench grinder, coupler and flexible shaft power take-off apparatus. The coupler is designed to secure the flexible shaft to the bench grinder so that a condition of dynamic balance will be present during rotation thereof.

[111' 3,822,513 [4 July 9,1974

BENCH GRINDER APPARATUS Inventor: Grover P. Holther, Jr., Mount Prospect, Ill.

Assignee: Electro' Engineering Products Co.,

Inc., Chicago, Ill.

Filed: Apr. 25, 1973 Appl. No.: 354,260

US. Cl. 51/168, 51/389 Int. Cl B24b 41/00, B24d 17/00 Field of Search....,.. 5l/l68, 169, 389;403/362 [56] References Cited UNITED STATES PATENTS 667,300 2/1901 Dilg et al. 51/389 1,334,224 3/1920 Campbell 51/389 FOREIGN PATENTS OR APPLICATIONS 498,052

Primary Examiner-James L. Jones, Jr. Attorney, Agent, or Firm-Dressler, Goldsmith, Clement & Gordon, Ltd.

[57] ABSTRACT A tool assembly includes a bench grinder, coupler and flexible shaft power take-off apparatus. The coupler is designed to secure the flexible shaft to the bench grinder so that a condition of dynamic balance will be present during rotation thereof.

4 Claims, 3 Drawing Figures l/1939 Great Britain 403/362 1 BACKGROUND OF THE INVENTION vices for polishing, cutting, etching, grinding and engraving are attached. The other end of the flexible shaft is provided with a coupler for attachment to the motor shaft. The coupler may be integral with the flexible shaft or a separate member. In the latter type coupling, one end of the coupler is attached to receive the flexible shaft and the other end is attached to be mounted on the grinder motor shaft.

It will be appreciate that. bench grinders rotate at high speeds so that dynamic balance and safety are primary considerations in the design of the coupler and flexible shaft. While there are several bench grinder apparatuses available in the market, the grinders, couplers and power take-offs suffer certain inadequacies relatingto dynamic balance andsafety. From a safety standpoint, rotating parts should be constructed so as to not haveprojections extending therefrom which may I catch or entangle the clothing or fingers of the opera- SUMMARY OF THE INVENTION The present invention relates to an improved bench grinder apparatus which may be safely operated at high speeds, with or without a flexible shaft attachment. The bench grinder system utilizes a threaded motor shaft onto which a coupler is threaded. The rotation of the grinder motor is opposite to the thread direction on the motor shaft so that the coupler is positively engaged with the shaft during rotation. The other end of the coupler opposite the threaded end is formed with an enlarged cross section, and the enlarged end of the coupler is provided with a chamber coaxial with the threaded portion of the coupler into which the flexible shaft is inserted and secured. The enlarged cross section is provided with a radial recess and threaded passage into which a flexible shaft securing screw is DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view, partially broken away, illustrating the bench grinder apparatus of the present invention;

FIG. 2 is an exploded view, partially in cross section, illustrating the elements shown in FIG. 1; and

FIG. 3 is a cross section of a coupler with the screw removed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will hereinafter be described in detail, a preferred embodiment with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiment illustated and described. The scope of the invention will be pointed out in the appended claims.

The bench grinder apparatus of the present invention provides a tool system that may be operated at high speeds without danger of entanglement and injury to the user and which is convenient to use due to the functional relationship between the coupling device and grinder motor shaft and the coupling device and flexible shaft power take-off. T

The coupling device is designed to be threaded onto the motor shaft of the grinder in the direction opposite to rotation, thus assuring that the coupler will not loosen or separate during rotation. The coupler has an enlarged cross-sectional area about the end in which threaded. Theme of the enlarged cross-sectional por- V with or without the flexible shaft coupled thereto.

These features make the grinding apparatus of the present invention particularly useful from convenience and safety standpoints.

the flexible shaft may be secured. This enlarged cross section and its added mass combined with a screw for securing the end flexible shaft in the coupler, provides a novel means for balancing the apparatus and preventing dangerous protuberances, as will be discussed below.

The grinder apparatus is shown in FIGS. 1 and 2, and

, includes a coupler 10 which is mounted to the endof the motor shaft 40 of a bench grinder 30 atone end and receives a power take-off flexible shaft assembly 20 at the other end. The grinder 30 consists of a motor and housing 31 which may be positioned, as by bolting, on

a support surface (not shown) by base portion 32 topermanently affix the system. The motor shaft 40 of the grinder is normally double ended, that is, capable of mounting grinding wheels or polishers on both the left and righthand ends of the power shaft. FIG. 1 illustrates the righthand portion of a typical grinder on which a grinding wheel 33 is mounted on shaft 40 by a bearing engagement with the grinding wheel. Wheel guard 34 is open on the outer side to accommodate the mounting of the grinding wheel 33 on shaft 40. The open side of wheel guard 34 is provided with a removable cover plate 35 which is generally circular in shape and mounted to wheel guard 34 by means of radially spaced bolts 36 about the circumference of the cover plate 35. The center of the cover plate 35 is provided with a circular opening 350, FIG. 2, through which the end of threaded shaft 40 extends.

The flexible shaft assembly 20 which is coupled to the grinder shaft 40 by coupler 10 includes an inner coupler will be in dynamic balance during rotation and no protrusions will be present to entangle the user. The coupler of the present invention is designed to be in dynamic balance not only when the shaft 21 is mounted therein, but also when there is no flexible shaft mounted therein so that the coupler may remain on the grinder shaft 40 at all times.

Coupler consists of a generally tubular shaped member having an internally threaded portion 11a, defined by an annular wall, adapted to be mounted on the end of the threaded grinder shaft 40. The threads within portion 11a are opposite to the direction of rotation of the grinder so that the coupler 10 will not become unthreaded from the shaft when torque is applied to the coupler by a loading on shaft 21.

Formed coaxially with threaded passage 11a is a shaft connection chamber 12 into which the flexible shaft 21 is inserted. Connection chamber 12 is surrounded by a wall 111) of increased cross section, as compared to the cross section at the threaded end 110. This increased cross section, which may be of any shape susceptible to balancing, preferably circular, provides a means for balancing the coupler during rotation thereof by increasing the total cross-sectional thickness so that a threaded radial passage 13 and recess 14 may be formed within the coupler. By providing recess 14, the screw means 15, illustrated as a fillister head machine screw, may be contained within the recess so that only the smooth surfaces of the head 17 will be exposed; preferably the entire head is received in chamber 14.

In the preferred embodiment, the passage 13 is designed to accept the thfeaded shaft 16 of the screw and is sized to allow the end thereof to engage the surface of shaft 21. It should be noted that shaft 21 may be formed with a screw seat 21a but is preferably formed with a smooth circular surface so that no eccentricity will be created therein. By sizing passage 13 so that the screw 15 engages shaft 21 when the head 17 of the screw is contained within recess 14, no protrusions will be presented that might entangle the user.

Preferably, the screw 15 is designed so that the volume of the head 17 and shaft 16 approximates the volume of recess 14 and passage 13 so that a condition of substantial dynamic balance will be presented when the screw seats, i.e., when the lower surface of the screw head 17 seats in recess 14,when no flexible shaft is present in chamber 12 or when the end of shaft 16 seats against shaft 21 when a flexible shaft is coupled. To enhance the balance of the coupler 10, it is preferable that the material from which the screw 15 is fabricated be the same as the material used for fabricating the coupler 10, or be of similar density.

It will be understood by those skilled in the art that variations and modifications of the specific embodiment described above may be employed without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. Bench grinder apparatus including: a bench grinder having a threaded motor driven shaft extending outwardly therefrom; a generally tubular shaped coupler having an internally threaded portion at one end adapted to be threaded on said motor shaft in a direction opposite to said shafts rotation, and an enlarged cross-sectional portion at the other end, said enlarged portion including a shaft connection chamber coaxial with said threaded portion and having a radially disposed, at least partially threaded passage extending therethrough to said connection chamber; screw means adapted to be threaded in said passage, said screw means having substantially the same volume as said passage and being adapted to extend into said connection chamber when seated; and a power take-off shaft adapted to be secured in said connection chamber, whereby said grinder and coupler are in substantial dynamic balance during rotation.

2. Bench grinder apparatus as set forth in claim 1 wherein said screw means is a machine screw and said enlarged portion further defines an annular recess coaxial with said passage at the outer surface thereof, the depth and shape of said recess corresponding to the size of the head of said screw, whereby the head of said screw may be received in said annular recess when said screw is seated.

3. Bench grinder apparatus as set forth in claim 1 wherein said coupler and screw means are formed of material having the same density.

4. Bench grinder apparatus as set forth in claim 1 wherein said enlarged portion of said coupler is circular in cross section. 

1. Bench grinder apparatus including: a bench grinder having a threaded motor driven shaft extending outwardly therefrom; a generally tubular shaped coupler having an internally threaded portion at one end adapted to be threaded on said motor shaft in a direction opposite to said shaft''s rotation, and an enlarged cross-sectional portion at the other end, said enlarged portion including a shaft connection chamber coaxial with said threaded portion and having a radially disposed, at least partially threaded passage extending therethrough to said connection chamber; screw means adapted to be threaded in said passage, said screw means having substantially the same volume as said passage and being adapted to extend into said connection chamber when seated; and a power take-off shaft adapted to be secured in said connection chamber, whereby said grinder and coupler are in substantial dynamic balance during rotation.
 2. Bench grinder apparatus as set forth in claim 1 wherein said screw means is a machine screw and said enlarged portion further defines an annular recess coaxial with said passage At the outer surface thereof, the depth and shape of said recess corresponding to the size of the head of said screw, whereby the head of said screw may be received in said annular recess when said screw is seated.
 3. Bench grinder apparatus as set forth in claim 1 wherein said coupler and screw means are formed of material having the same density.
 4. Bench grinder apparatus as set forth in claim 1 wherein said enlarged portion of said coupler is circular in cross section. 